The volume of water that must be added in order to dilute 40mL of 9.0M HCl to a concentration of 6.0 M is closest to: (A) 10 mL (B) 20 mL (C) 30 mL (D) 40 mL (E) 60 mL

We should add 60 mL (option E)

Explanation:

Step 1: Data given

Initial volume = 40 mL = 0.040 L

Initial molarity = 9.0 M

New molarity = 6.0 M

Step 2:

C1*V1 = C2*V2

⇒with C1 = the initial molarity = 9.0 M

⇒ with V1 = the initial volume = 0.040 L

⇒ with C2 = the new molarity = 6.0 M

⇒ with V2 = the new volume

9.0 * 0.040 = 6.0 * V2

V2 = 0.06 L = 60 mL

We should add 60 mL (option E)